Psychophysical experiments in UCSD will be undertaken with the principal aim of investigating retinal processes underlying perception. The experiments include: (1) studies of the minimally distinct border, (2) color discrimination, and (3) transient dichoptic masking. Human subjects will be used in all of this work. Electrophysiological experiments to be done in Dr. William Baron's laboratory at the Stanford Research Institute will be concerned with: (1) measurements of rod saturation of the photoreceptor stage, (2) measurements of light distribution in the primate eye, and (3) studies of area effects that reveal interactions among primate photoreceptors. Cynomolgus macaque monkeys will be used in this work. The overall aim of the project is to explore the first stages of visual information processing in an attempt to reduce the scope of what remains to be explained by the action of more central processing. BIBLIOGRAPHIC REFERENCES: Kelly, D.H., R.M. Boynton, and W.S. Baron. Primate flicker sensitivity: psychophysics and electrophysiology. Science, 194, 1077-1079 (1976). Boynton, R.M., M.M. Hayhoe, and D.I.A. MacLeod. The gap effect: chromatic and achromatic visual discrimination as affected by field separation. Optica Acta, 24, 159-177 (1977).